OBJECTIVE: To investigate the effects of synthetic glucocoticosteroids on the growth and cytokinetics of tumor cell populations from a variety of experimental tumor models in mice and rats and correlate these effects with specific glucocorticosteroid receptor levels. APPROACH: Utilizing a battery of experimental tumor systems in mice and rats, evaluate corticosteroid dose dependent effects on tumor growth and tumor cell proliferation. Studies will be initiated with methyl prednisolone, dexamethasone and triamcinolone acetonide. Cell kinetic measurements, 3H-TdR labeling index, mitotic index, DNA synthesis time and tumor growth fraction (PDP assay), will be determined prior to and at various intervals after short corticosteroid treatments so that the perturbing effects of these agents on cell proliferation can be evaluated. Sequential chemotherapy schedules with corticosteroids and cycle stage specific agents will be designed and tested to evaluate the therapeutic implications of the corticosteroid induced cell kinetic perturbations. Specific cytoplasmic glucocorticosteroid receptors, determined by the competitive binding dextran charcoal assay, will be evaluated in each model studied and correlated with the effects on tumor growth and cell proliferation. In this way we hope to elucidate relationships between corticosteroid receptor levels cell proliferation and response to therapy that are not only unique to individual models, but that also have more general applicability to all models.